of breeding, Darwin infers from the Struggle for Existence which, he says, is, under nature, constantly carried on, by all organisms, each with the others; whereby the weak succumb, and those which are the fittest, strongest, and most vigorous survive. Besides the selection of those which are the strongest, there will also be a selection of those which display some new modification; and these mating with their fellow victors in the struggle for life, will attain, through their offspring, to a higher and still higher development. Conformably to the theory of Malthus, he contends, that, under nature, the production of new organisms far outruns the means of their subsistence; that all Nature is at war, one species with another, and the individuals of the same species with each other. The result of this Struggle for Existence, is Natural Selection; by which, the lucky and the stronger prevail, and the weaker and ill-favored perish. As many more individuals are born than can possibly survive, those individuals which possess any variation which contributes to give them an advantage in this warfare, are, in the main, more likely to survive, to propagate, and to occupy the places of their weaker brethren, with their offspring. If but a single variation occurred once in a thousand generations, says Darwin; and that variation were preserved by Natural Selection, until, at the end of another thousand of generations, another variation was superadded, the improvement and diversity of the species would, eventually, be such as to occasion a divergence, by the different individuals favored, into distinct species.

The question of the origination of these improvements, or variations (which are modestly assumed to occur but once in a thousand generations), is equally left unresolved by Darwin, and referred, as are the variations under domestication, to "an innate tendency to vary," or to " spontaneous variability!"

It is impossible to deny, that there is such a Struggle for Existence, as Darwin pictures; and, equally impossible to deny, that there is some such process as Natural Selection, in operation under nature, favoring at times the preservation of the strongest and most fitted. It is scarcely possible, even, to read Darwin's graphic description of the Struggle for Existence, among animals and plants, under nature, and not marvel that any survived. Under nature, he says, organisms are subjected to the greatest vicissitudes, and to the severest competition with their fellows, with other species, and with the adverse conditions of nature. They all enter into competition, for the means of subsistence. All, almost without exception, he says, have to struggle against the hard conditions of life, and against their competitors, from the moment of their birth, to the hour of their death. He alleges, that there is no exception to the rule, that every organic being naturally increases at so high a rate that, if numbers were not destroyed, the earth would soon be covered with the progeny of a single pair. The struggle, he holds, will almost invariably be the most severe, between the individuals of the same species; for, they frequent the same districts, require the same food, and are exposed to the same dangers. Consequent upon

the astonishingly great increase, is the Natural Extinction of large numbers.

Those whom nature exempts from this wholesale destruction, are naturally those which are the fittest to live, the strongest, and most vigorous; and, notably, those who "at intervals of a thousand generations" or so, have developed some character, or modification, which gives them an advantage, in the general contest for life, over their competitors, and over the hard conditions of life.

This selection, of the strongest and fittest, and of the favorably modified organisms, as the ones of the number ordained to live, is what constitutes Darwin's Natural Selection-a factor which depends necessarily upon this Struggle for Existence.

Natural Selection has nothing whatever to do, Darwin says, with the production, or appearance, of any of the variations or improvements. How any favorable modification, or variation, comes to present itself, Darwin insists that he is profoundly ignorant. But, after the variation has appeared, this Natural Selection merely preserves it, insures its transmission to offspring, and so accumulates successive variations which arise, independently of it, owing to “an innate tendency.” Natural Selection, Darwin says, does not at all cause the variations which may occur. Their origin is inexplicable to him, he says; but, “it acts exclusively by the preservation and accumulation of those variations after they have arisen." Variations occur in some strange way, by "accident or chance," independently of Natural Selection, though so to refer them to acci

dent or chance, is, he says, merely to express our ignorance of the law. Natural Selection but preserves and accumulates the variations as they arise, and directs them into favorable lines of growth. "As all the individuals of each district are struggling together with nicely balanced forces, extremely slight modifications in the structure or habits of one individual often give it an advantage over the others." And (what is part of the same Natural Selection, called Sexual Selection), were the individual varying, a male, the acquired modification would doubtless give it an advantage, in a contest for the most favored, and, perhaps, similarly varying, females; and, thereby, the modification acquired, would be the more surely impressed upon the offspring. In "several thousand generations," or a "million of generations," one of the descendants of this offspring would, probably, also vary, adding thus another character to the complexity of its structure.

As, under domestication, Man's care and choice of those animals and plants, displaying some improvement, tends to the preservation and accumulation of the characters presenting themselves, and assures the transmission of those characters to offspring; so, this Selection by Nature, of the favorably modified animals and plants, as among those which are suffered to survive and propagate their kind, represents the same principle.

"Can it be thought improbable," says Darwin, "seeing that variations useful to man, have undoubtedly occurred, that other variations, useful in some way to each being in the great and complex battle of life,

should sometimes occur in the course of thousands of generations? If such variations do occur, can we doubt (remembering that many more individuals are born than can possibly survive), that individuals, having an advantage, however slight, over others, would have the best chance of surviving and procreating their kind?” "If," he continues, "a man can, by patience, select variations useful to him, why, under changing and complex conditions of life, should not variations, useful to nature's living products, often arise and be preserved and selected?"

Darwin asks, “What limit can be put to this power, acting during long ages, and rigidly scrutinizing the whole constitution, structure, and habits of each creature-favoring the good and rejecting the bad?” “I can see no limit to this power, in slowly and beautifully adapting each form to the most complex relations of life."

"Selection," continues Darwin, "will pick out, with unerring skill, each improvement. Let this process go on for millions of years, and may we not have a low primordial type" continuing to evolve into higher and still higher forms of life, until, at last, as the result of this "innate tendency to vary," producing improvements, and of this Natural Selection preserving these improvements, all of the higher animals, including Man, are successively evolved, by the gradual operation of strictly natural processes? In this way, Darwin contends, the present development, and diversity of structure, of the several species, have been effected; and in this way "some one low primordial form into